Quality Characteristics and Clinical Relevance of In-House 3D-Printed Customized Polyetheretherketone (PEEK) Implants for Craniofacial Reconstruction.

Neha Sharma,Shuaishuai Cao,Philipp Honigmann,Soheila Aghlmandi,Florian M. Thieringer,Christoph Kunz

doi:10.3390/jcm9092818

Abstract

Additive manufacturing (AM) of patient-specific implants (PSIs) is gradually moving towards in-house or point-of-care (POC) manufacturing. Polyetheretherketone (PEEK) has been used in cranioplasty cases as a reliable alternative to other alloplastic materials. As only a few fused filament fabrication (FFF) printers are suitable for in-house manufacturing, the quality characteristics of the implants fabricated by FFF technology are still under investigated. This paper aimed to investigate PEEK PSIs fabricated in-house for craniofacial reconstruction, discussing the key challenges during the FFF printing process. Two exemplary cases of class III (Group 1) and class IV (Group 2) craniofacial defects were selected for the fabrication of PEEK PSIs. Taguchi’s L9 orthogonal array was selected for the following nonthermal printing process parameters, i.e., layer thickness, infill rate, number of shells, and infill pattern, and an assessment of the dimensional accuracy of the fabricated implants was made. The root mean square (RMS) values revealed higher deviations in Group 1 PSIs (0.790 mm) compared to Group 2 PSIs (0.241 mm). Horizontal lines, or the characteristic FFF stair-stepping effect, were more perceptible across the surface of Group 1 PSIs. Although Group 2 PSIs revealed no discoloration, Group 1 PSIs displayed different zones of crystallinity. These results suggest that the dimensional accuracy of PSIs were within the clinically acceptable range; however, attention must be paid towards a requirement of optimum thermal management during the printing process to fabricate implants of uniform crystallinity.

Highlights

Craniofacial reconstructions are often time consuming and present a significant challenge for the surgeon
We present an investigation on the influence of printing process parameters on the dimensional accuracy of fused filament fabrication (FFF) 3D printed PEEK patient-specific implants (PSIs)
analysis of variance (ANOVA) and S/N ratio analysis were conducted to identify the optimum combination of process parameters

Summary

Introduction

Craniofacial reconstructions are often time consuming and present a significant challenge for the surgeon. A typical application is a cranioplasty, which is a standard neurosurgical procedure performed to reconstruct cranial defects. The critical clinical challenges in the reconstruction of craniofacial bone defects are the ability to carry out complex reconstructions with precise implant fit and esthetic appearance. The cumulative understanding of the surgeon to overcome these clinical challenges have led to the utilization of prefabricated patient-specific implants (PSIs) for cranioplasty procedures [1,2,3]. PEEK is an aromatic polymer with ether and ketone bond linkages. It is a high-temperature, semicrystalline thermoplastic material, which is chemically inert with high thermal stability and mechanical properties. Combining the characteristics intrinsic properties of PEEK, such as no artifact in medical imaging along with cortical bone-like modulus, it is an excellent alternative for metallic biomaterials in craniomaxillofacial reconstructive surgeries [6,7,8]

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